Blu-ray vs DVD: A Look at the Differences

Blu-ray discs have taken the place of DVD ones with people who need something a little bit better or simply more storage capacity. The number of extras on a disc is also massively expanded, so movie studios can include a director’s cut, an alternate ending, or a bunch of extras that wouldn’t ordinarily fit on a DVD disc.

Storage Limitations

Storage is measured in gigabytes (GB) of data. The greater capacity, the more a disc can store.

With DVD discs, they are either single-layer with a 4.7GB capacity or dual-layer with an 8.7GB capacity. The former is referred to as DVD-5 and the latter as DVD-9. Currently, not every DVD player supports the DVD-9 as it is newer. The original 4.7GB is large enough to store a two-hour movie and a few extras; the latter 8.7GB can store a four-hour movie.

With Blu-ray discs, there are also single-layer discs and ones known are double-layer discs. The former stores 25GB of files and the latter 50GB of files. Blu-ray discs are often used to store 4K UHD video content that goes beyond the Full HD standard, so the image quality is potentially superior. Between two and 13 hours of video content is storable on the single-layer Blu-ray discs and double this capacity for their double-layer cousins.

The Technology

DVD players spin the disc while reading it. They use a 650nm red laser to extract information to display both image and sound on a screen. Blu-ray discs, as the name indicates, uses a blue laser configured to 405nm. The Blu-ray laser is narrower and therefore can collect information more tightly packed on the disc.

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It’s All About the Resolution

DVDs can store a 1080p video file, but it’s pretty crammed in. It doesn’t leave much space for the DVD extras like a commentary soundtrack or a behind the scenes documentary.

With Blu-ray discs, 1080p resolution is commonplace, but higher resolutions up to 4K (which is twice the width and twice the height) are possible too. The flexibility and greater storage capacity give TV and movie studios more choices about how they configure their discs, the quality of the media and what extras they include too.

Can You Play It?

The good news is that while you do need a Blu-ray player to play these discs, the players are fully backward compatible with various DVD discs like the DVD-5 and the newer DVD-9 formats. Whether it’s a Blu-ray drive inside your computer, a PlayStation console with its own Blu-ray drive or an external USB Blu-ray drive, they all offer this feature. The same isn’t true for playing Blu-ray discs inside a DVD player because the red laser from the DVD machine cannot read the smaller grooves storing information on the Blu-ray disc.

Moving up from DVD to Blu-ray is the next step in digital media. If you want the best resolution and image quality for your big-screen TV, then Blu-ray is the way to go. Being able to keep your existing DVD collection and use it too is just the icing on the cake.